I would suggest, if possible, remove the yellow tang and blue surgeon and try to trade with a fish store. I love my Midas Blenny and I would highly recommend this as a replacement. Your Maroon Clownfish will be quite aggressive to any other clownfish, so I'd stay away from those. As long as your water quality stays high, I wouldn't say it's urgent to do this, just better in the long run for the fish.